High Efficiency White Organic Light‐Emitting Devices Incorporating Yellow Phosphorescent Platinum(II) Complex and Composite Blue Host. (2nd May 2013)

• Record Type: Journal Article
• Authors: Lai, Shiu‐Lun; Tong, Wai‐Yip; Kui, Steven C. F.; Chan, Mei‐Yee; Kwok, Chi‐Chung; Che, Chi‐Ming
• Is Part Of: Advanced functional materials. Volume 23:Number 41(2013)
• Page Start: 5168
• Page End: 5176
• Publication Date: 2013-05-02
• Subjects: Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201300281
• Languages: English
• ISSNs: 1616-301X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A new class of charge neutral, strongly luminescent cyclometalated platinum(II) complexes supported by dianionic tetradentate ligand are synthesized. One of these platinum(II) complexes, <bold>Y‐Pt</bold>, displays a high photoluminescence quantum yield of 86% and electroluminescence efficacy (<italic>η</italic><sub>power</sub>) of up to 52 lm W<sup>−1</sup>, and is utilized as a yellow phosphorescent dopant in the fabrication of white organic light‐emitting devices (WOLEDs). WOLEDs based on conventional structures with yellow emission from <bold>Y‐Pt</bold> in combination with blue emission from <italic>bis</italic>(4, 6‐difluorophenyl‐pyridinato‐<italic>N</italic>, <italic>C<sup>2</sup></italic>′) (picolinate) iridium(III) (FIrpic) show a total <italic>η</italic><sub>power</sub> of up to 31 lm W<sup>−1</sup>. A two‐fold increase in <italic>η</italic><sub>power</sub> by utilizing a modified WOLED structure comprising of a composite blue host is realized. With this modified device structure, the total <italic>η</italic><sub>power</sub> and driving voltage at a luminance of 1000 cd m<sup>−2</sup> can be improved to 61 lm W<sup>−1</sup> and 7.5 V (i.e., 10 V for control devices). The performance improvement is attributed to an effectively broaden exciton formation‐recombination zone and alleviation of localized exciton accumulation within the FIrpic‐doped composite host for reduced triplet‐triplet annihilation, yielding blue light‐emission with enhanced intensity. The modified device structure can also adopt a higher concentration of <bold>Y‐Pt</bold> towards its optimal value, leading to WOLEDs with high efficiency.</p> </abstract>